Neutral Wire

[dude_with_beard]

So I bought a sonoff smart RF 3gang light switch.
not sure how to tell which is the neutral wire and whether this will work.
Is it easy enough to do my self or should I just call an electrician?
also, where else can I buy sonoff stuff besides from takealot?

 

[dude_with_beard]

Not sure how to tell which is the neutral wire? If you're asking for help you're going to have to provide more info.

A photo will help, otherwise at least a description.

On the house wiring side, neutral will be black (or sometimes blue).

There's a good chance your existing switch does not have neutral, in which case you'll have to run neutral from an ecisting source in the ceiling. You'll need to cut and join inside a box up there - should be the easiest.

Im not sure what it’s meant to look like but this is mine

 

[Geoff.D]

The red wire in the picture is more than likely the lIve wire, with the white wires being live to the light fittings. Not too clear if the switch plate is metal.? If it is, the blue or maybe the black wire is being used earth. There is no sign of an earth wire in the photos, which should be either yellow/green or a bare copper wire.

 

[Grubscrew]

Perhaps get an electrician to do it?

 

[Geoff.D]

Perhaps get an electrician to do it?

Yes maybe. BUT, looking at the quality of the work in the photo, it is typical of electrical short cuts taken in the industry these days and those are all "electricians" doing the work.

 

[D tj]

The Neutral is likely only at the light fitting, Red live in, the blue and white Live to light fitting, as this is only the light switch box.
This my take from pictures.

 

[Grubscrew]

Yes maybe. BUT, looking at the quality of the work in the photo, it is typical of electrical short cuts taken in the industry these days and those are all "electricians" doing the work.

Correct but that "electrician" isn't the one trying to do how-to from the internet. Also DIY electrics will void your CoC and some insurers love to look for a reason not to pay out on house fire claims...

 

[quovadis]

There generally isn't a neutral wire a light switch box - it'll be on the other side of the lamp. So you have the live enter, then the live continues through the switch to the lamp and then from the lamp to neutral. It's not 100% clear from the pictures provided but you would generally require a neutral from the lamp back to the switch or bring one from the DB to the switch. I'm not a electrician but most home automation requires a neutral wire and most SA installations don't have those in switch boxes.

 

[Geoff.D]

Correct but that "electrician" isn't the one trying to do how-to from the internet. Also DIY electrics will void your CoC and some insurers love to look for a reason not to pay out on house fire claims...

Well, I have "seen" the results of a so-called CoC exercise done on the place my daughter purchased, and the incredible "mistakes" that were "signed off". So, I have absolutely zero faith in the entire CoC process as implemented currently.

 

[Geoff.D]

There generally isn't a neutral wire a light switch box - it'll be on the other side of the lamp. So you have the live enter, then the live continues through the switch to the lamp and then from the lamp to neutral. It's not 100% clear from the pictures provided but you would generally require a neutral from the lamp back to the switch or bring one from the DB to the switch. I'm not a electrician but most home automation requires a neutral wire and most SA installations don't have those in switch boxes.

No, not so. Most home built before 1994 had an earth wire in every lightbox which was a bare copper conductor, and a system whereby the "live" feed into the box consisted of a Red live and black neutral wire. Neutrals were NOT commoned in the ceiling daisy-chained from one fitting to another.
It is pretty recent that the so-called "regulations" were changed to allow twin earth wiring to plastered into walls where the "rot" set in.
And btw, the "Live" feed was always red and black, with the feeds to light fittings being red and blue, not any old colour and certainly not white either.

The new standards introduced after 1994, are an absolute joke.

 

[D tj]

^^ @ quovadis if the pictures are as it appears of a light switch and it's box, there would be no neutral unless passing through to another light fitting....the neutral has no job in the light switch box....the switch breaks the live only.

 

[Geoff.D]

^^ @ quovadis if the pictures are as it appears of a light switch and it's box, there would be no neutral unless passing through to another light fitting....the neutral has no job in the light switch box....the switch breaks the live only.

BS!. The neutral in a lightbox makes the wiring understandable, logical and flexible! Especially when introducing modern facilities such as OP is trying to do.

The issue is the older regulations saw to it that there were no "hidden" connection points anywhere. The connections were all in boxes easily accessible.
These "changes" have introduced a myriad of hidden connecting points in ceilings and walls.

 

[Dairyfarmer]

A switch does not carry the neutral wire. It is only there to break the live (i.e. cut power to the light). A good electrician would also connect the earth wire to the switch.

From your DB board a red wire (permanent live) runs to the switch. It goes in one side and comes out the other and goes to the fitting (switched live). A good electrician will use a white or blue wire from the switch to the fitting. That way you know which is the permanent live (red) and the switched live (white or blue).

To cut corners an electrician will run a 3 core wire to the switch using the red as permanent live and black as switched live. So the fitting may have two black wires. I have even seen some people use the earth wire as a second switched live.

NOTE: Always isolate the neutral at a 2 or 3 pole isolator. This is either the main switch or green earth leakage that has 2 wires going through it. Don't just turn the single pole isolator (trip switch). The neutral can still give you a shock.

EDIT: also note that many electricians tell you that lights don't need to be earthed so the live to the lights trip switch may not run through an earth leakage. So getting a shock and the electricity will want to travel through your body rather than the earth shortcut.

 

[Dairyfarmer]

BS!. The neutral in a lightbox makes the wiring understandable, logical and flexible! Especially when introducing modern facilities such as OP is trying to do.

Can't say I have ever seen a switch with a neutral wire.

 

[Geoff.D]

A switch does not carry the neutral wire. It is only there to break the live (i.e. cut power to the light). A good electrician would also connect the earth wire to the switch.

From your DB board a red wire (permanent live) runs to the switch. It goes in one side and comes out the other and goes to the fitting (switched live). A good electrician will use a white or blue wire from the switch to the fitting. That way you know which is the permanent live (red) and the switched live (white or blue).

To cut corners an electrician will run a 3 core wire to the switch using the red as permanent live and black as switched live. So the fitting may have two black wires. I have even seen some people use the earth wire as a second switched live.

Unfortunately, the new way of plastering into the wall twin earth cable has caused all sorts of short cuts such as being "forced" to make use of whatever wires there are available.

The "old" regulations saw to it that there were always "enough" wires available in a multi-light switch. So, if the light switch was for a single switch, there would be:

Bare copper earth
Red & Black "Live Feed" from the DB.
Red and Blue "Load Feed" to the light fitting.

If there was more than one "switch" there would a "Load Feed" consisting of two conductors for each light fitting.
And it would have all been in conduits.

 

[Dairyfarmer]

Best example of a light wiring. The Yellow is the earth wire. The dark wire is the live and the light wire is the neutral. The live is always the one that comes from the single trip switch.

 

[AchmatK]

Opened this thread and decided to check my light switch.

No idea what's going on and if there's a neutral wire in here and what the black wire is for.

This is the single light switch in my bedroom.

 

[Geoff.D]

Opened this thread and decided to check my light switch.

No idea what's going on and if there's a neutral wire in here and what the black wire is for.

This is the single light switch in my bedroom.

The Bare Cu plus green yellow is the Earth.
The 3 black wires are the neutrals.
Three wires are the live feeds into the switch, plus the power feed to the light fitting, plus a daisy-chained "Live Feed" to the next light switch.
Can't see if one of the "black wires is not, in fact, a blue wire.

That is how it used to be done. The green-yellow indicates that there was a later extension done to another light switch at a later date after the original installation, hence the daisy-chained "Live Feed".

 

[AchmatK]

The Bare Cu plus green yellow is the Earth.
The 3 black wires are the neutrals.
Three wires are the live feeds into the switch, plus the power feed to the light fitting, plus a daisy-chained "Live Feed" to the next light switch.
Can't see if one of the "black wires is not, in fact, a blue wire.

That is how it used to be done. The green-yellow indicates that there was a later extension done to another light switch at a later date after the original installation, hence the daisy-chained "Live Feed".

Thanks.

The 3 black as are black with no blue in there.

House was built in the mid seventies so pretty old house.

Edit the next switch after this one is for the light in Ensuite. Nothing after this one.

Hope it's the same in all the switches so it should be ready to get one of the smart switches installed.

 

[quovadis]

The Bare Cu plus green yellow is the Earth.
The 3 black wires are the neutrals.
Three wires are the live feeds into the switch, plus the power feed to the light fitting, plus a daisy-chained "Live Feed" to the next light switch.
Can't see if one of the "black wires is not, in fact, a blue wire.

That is how it used to be done. The green-yellow indicates that there was a later extension done to another light switch at a later date after the original installation, hence the daisy-chained "Live Feed".

I would've said the green/yellow = Earth. 1x Red = Live from DB and 3 other reds are loads (ie. lamps). Blacks probably neutrals. Would be nice to see how many switches on the front. But we're on the same frequency I think.